1. Technical Field of the Invention
This invention relates to epoxy curing agents and more particularly to polyoxyalkylene amines and the reaction thereof with epoxides in the presence of acetone to form compositions generally useful as epoxy curing agents. Some of these compositions exhibit additional desirable properties.
In one embodiment polyoxypropylene triamines, such as JEFFAMINE.RTM. T-series amines are reacted with epoxides to form light colored, fluid hydroxyhexamines. In another embodiment polyoxyalkylene diamines, such as JEFFAMINE.RTM. D-series and ED-series amines are reacted with epoxides, such as, for example Bisphenol A epoxy resins to form amine terminated, light colored liquids with a wide range of viscosities.
2. Related Art
It is well known that various polyamine compounds are widely used as raw materials for hardening agents of epoxy resins. For these resins, typical examples of useful polyamine compounds are aliphatic amines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, etc.; aromatic amines such as phenylenediamine, diaminophenylmethane, diaminophenylsulfone, etc.; aliphatic amines having aromatic ring, such as xylylenediamine, etc.; and alicyclic amines such as bisaminomethylcyclohexane, isophoronediamine, etc. These polyamine compounds each has a reactivity of the amino group as the specific feature caused by the active hydrogen and they are used for various purposes. Further, polyamine compounds which have been modified in a manner suitable for the specific polyamine compound have found a variety of uses and the modified compounds are used as hardening agents for epoxy resins.
Adducts from amines and diepoxides have long been used in industry as curing agents for epoxy resins.
It is known from U.S. Pat. No. 3,538,184 (November 1970) that a polyglycidyl ether can be reacted with a hexamethylenediamine to form solvent free liquid adducts of polyepoxides and polyamines which are suitable for use as curing agents for epoxy resins.
In U.S. Pat. No. 3,629,181 there is described a curing agent which comprises the adduct from a polyglycidyl ether of a polyphenyl and a cycloaliphatic or cycloaliphatic-aliphatic di-primary diamine, in which at least one of the primary amino groups is bonded to an endocyclic carbon atom of a cycloaliphatic ring.
In U.S. Pat. No. 3,996,175 there are described moulding materials from epoxide resins based on Bisphenol A or on other bis- or polyphenols and epichlorohydrin which contain aromatic amines as curing agents.
U.S. Pat. No. 4,348,505 discloses the preparation of amine adduct curing agents utilizing epoxides of a functionality greater than two which dramatically enhance the chemical resistance properties of the cured epoxy products over results obtained from either free amines or the conventional amine adducts.
In U.S. Pat. No. 4,540,750 it was disclosed that the preparation of diethyl toluene diamine adduct curing agents with epoxides of a functionality of at least two enhances the performance characteristics of cured epoxy and urethane products.
U.S. Pat. No. 4,578,412 is directed to modified (i.e. extended) amine curing agents which are prepared by dissolving a solid elastomeric polyurethane such as RIM polyurethane in an amine of the type used for curing epoxy resins.
A novel polyamine compound made by reacting m-xylyene diamine and epichlorohydrin in the presence of an alkali which is useful as a hardening agent for epoxy resins is disclosed in U.S. Pat. No. 4,605,765.
There are described in U.S. Pat. No. 4,608,404 compositions which contain specific groups of oligomeric diamine hardeners and epoxy compounds which when combined with structural fibers produce composites which have improved tensile properties, high compressive strengths and improved impact resistance and, in addition, demonstrate low moisture absorption.
In an article titled "High Solids Epoxy/Polyamide Coatings", V. Brytus discusses a new polyamide hardener which overcomes the compatibility problem brought about by reducing the molecular weight of epoxy/polyamidoamine maintenance coatings in an attempt to lower the volatile organic content. See Journal of Coatings Technology, Vol. 58, No. 740, September 1986. The polyamide has controlled levels of imidazoline and other constituents having an affinity for the Bisphenol A moiety. A two-step method of producing N,N'-dimethyl diamine compounds for use as epoxide polyaddition compounds is described in U.S. Pat. No. 4,623,746. The resins formed using this compound as a curative can be produced with improved strength, toughness and hot/wet properties.
Wang et al disclose in U.S. Pat. No. 4,636,535 curable compositions comprising epoxide prepolymers and polyamidobenzoates, alone or combined with reinforcements such as graphite fibers.
In U.S. Pat. No. 4,680,341 epoxy resin systems are disclosed which exhibit good tensile properties and good moisture sensitivity which are made by copolymerizing tetraglycidates with a polyamine curing agent.
From the preceding discussion it is apparent that compositions with a variety of properties which are the product of a wide range of amine and epoxide components are useful in the field of epoxy curing resins.
It is believed that a method for extending the molecular weight of certain triamines would provide compositions with a number of uses. Hexamines containing functionalities of hydroxy and Bisphenol A would have particularly desirable characteristics. Further, amine terminated compositions with a wide range of predictable viscosities would have many uses for those skilled in the art of epoxy curing resins.